"The soil of the Earth itself can provide the best shelter for most catastrophes, including a pole shift, super volcano eruptions, solar flares, earthquakes, asteroids, tsunamis, nuclear attack, bio terrorism, chemical warfare and even widespread social anarchy," Vivos states on its website.

The answer, Mr Vicino tells www.news.com.au, is underground bunkers.

The expensive ones hold up to 250 people and give them some 50 square metres of personal space each.

They start at $US25,000 a share, but with time running out, Mr Vicino is offering a discount option.

If you've got $US10,000 to spare, you're guaranteed at least six months' safety in a less-cosy, yet just as Armageddon-proof, 30,000 square metre bunker, shared with 1000 people.

"What was previously perceived by many to be a survival solution only for the ‘elite’, is now affordable to virtually anyone wanting a ‘boarding pass’ into an impervious Vivos shelter to survive Armageddon, or whatever cataclysms may be ahead for our planet," he says.

Mr Vicino said about 10,000 shares in various bunkers had already been sold and that the cheaper option doesn't mean you'll be more at risk.

"Just shorter duration of supply for guaranteed autonomous sheltering before you need to return to the surface," he told www.news.com.au.

But with the shelters based in the central United States, when will you know it's time to make the trip and start your six- or 12-month stay?

Mr Vicino's first goal is to have one bunker open in time for the when the inbound Comet Elenin threatens Earth in the US autumn.

But he told news.com.au members can come in "whenever there is an emergency need to do so".

"They own their respective shelter and can go there whenever a catastrophic risk is predicted, happening or in the aftermath. "They just can’t live or stay there for other personal reasons."

He offered these guidelines for various scenarios:

Comet Elenin – "We will have weeks to months of notice if it is going to have an impact on Earth."

Terrorism threats – "If the threat is real or specific to the area; or, if something happens in another area (e.g. dirty bomb in NYC), then it would be a good time to head to the shelter."

EMP – "That will likely come without notice, but you will have time to get to the shelter before society breaks down (3 to 7 days later)."

Solar flares – "Same as EMP, but the solar activity can be monitored and will give warnings."

Tsunami – "Typically a result of one of the above issues. Again, there should be warnings."

But he said it was important to remember that "nothing happens unexpectedly".

"Everything has an indication. We just have to observe the connections," he said.

"We will send out an alert, but they don’t have to wait if the threat is already known."

Vivos hopes to have a dozen shelters available all up, able to accommodate 6000 people - roughly one for every million on Earth.

He said two shelters were in their final stages and three more in the works.

As for the psychological implications of housing 1000 strangers underground for at least six months, Mr Vicino told www.news.com.au that they were "better than trying to survive on the surface".

"If we are locked down in the shelter there is a reason for it," he said.

"We have psychiatrists, doctors, surgeons, nurses and medical experts (actual members) within each shelter to make the best of it."

And in case you were wondering, Mr Vicino believes the most likely end-of-days scenario will come from a solar flare.

And yes, he'd consider versions in Australia.

"If we get a critical mass of members – ready, willing and able to purchase their share(s) in a shelter," he said.